Essentially, can the slack api for incoming webhooks create a private channel and invite certain users (more than 1). I understand how it works to send to a specific channel or a specific person, but not quite sure with multiple.
Thanks!
No, you can not create new channels - e.g. to create a group chat - with in incoming webhook. You have to specify an exciting channel when sending a message with it. Incoming webhooks are meant to provide an easy (and relatively safe) way to send messages to Slack channels. If you need more advanced features, please have a look at the API.